A multidimensional-crack-growth prediction methodology for flaws originating at fastener holes

A multidimensional-crack-growth prediction methodology for flawed fastener holes is described. The methodology uses a slice-synthesis model of the flawed hole for predicting the crack-driving force around the periphery after each increment of advance. Analytic predictions of the crack-growth rate are compared with test results for various examples. It is shown that residual stresses due to yielding at the hole edge and the cycle-by-cycle shape changes are a major cause of apparent crack-growth retardation or acceleration, and that the assumption of a constant shape, as is a common practice, can lead to highly misleading estimates of service life.